A while ago I came across the following one page online article which nicely describes NMOS and its key objectives.
I'm at this moment not able to provide you with more insights on how widely adopted it is already. We do however see that the latest new ST2110 compliant media equipment appears to offer an NMOS (IS-04 / IS-05) or an Ember+ interface. Sometimes even both, but typically the vendors now appear to offer the choice at order time, whether the media equipment should expose an NMOS API or should expose an Ember+ API.)
Ember+ (brought to existence by Lawo but with the same plug and play type of behavior envisioned) appears to be competing with NMOS at the moment as this standard got adopted a bit sooner by already a range of broadcast equipment / controllers.
There's already some broadcast controllers out there which are compatible with both protocols. So they can handle a hybrid environment where part will be controlled over NMOS, part over Ember+ and partly vendor bespoke API's.
Personally I do believe that NMOS will eventually win over Ember+ in popularity as it offers many more advantages and standardization which Ember+ does not but only the future will tell us that.